Include additional upstream changes to postinst

This mostly removes a bunch of vestigal stuff and stops overwriting
/etc/dpkg/origins/default every upgrade.

Change-Id: Ia6fe76f691118c81a450cc997602ee8a33ffe2cd

debian/postinst.in

diff --git a/debian/postinst.in b/debian/postinst.in
index 0393a4f..a8c646c 100644
--- a/debian/postinst.in
+++ b/debian/postinst.in
@@ -44,13 +44,13 @@
   fi
 }
 
-if [ -e /etc/dpkg/origins/#VENDORFILE# ]; then
-  ln -sf /etc/dpkg/origins/#VENDORFILE# /etc/dpkg/origins/default
+if [ ! -e /etc/dpkg/origins/default ]; then
+  if [ -e /etc/dpkg/origins/#VENDORFILE# ]; then
+    ln -sf /etc/dpkg/origins/#VENDORFILE# /etc/dpkg/origins/default
+  fi
 fi
 
 if [ "$1" = "configure" ] && [ "$2" = "" ]; then
-  install_from_default staff-group-for-usr-local \
-                                     /etc/staff-group-for-usr-local
   install_from_default dot.profile   /root/.profile
   install_from_default dot.bashrc    /root/.bashrc
   install_from_default profile       /etc/profile
@@ -120,8 +120,3 @@
     install_directory mnt 755 root
   fi
 fi
-
-if dpkg --compare-versions "$2" lt-nl "6.10"; then
-  install_from_default staff-group-for-usr-local \
-    /etc/staff-group-for-usr-local
-fi

debian/rules

diff --git a/debian/rules b/debian/rules
index 5e36c4b..27740f3 100755
--- a/debian/rules
+++ b/debian/rules
@@ -49,5 +49,3 @@
 	cd debian/base-files && chmod 1777 `cat ../1777-dirs`
 	cd debian/base-files && chmod 2775 `cat ../2775-dirs`
 	cd debian/base-files && chmod 700 root
-
-install: